Track and other rail assets can be difficult to access, and are often hidden from view. However, rail engineers are learning to rise above these problems and there is growing interest in the use of unmanned aerial vehicles (UAVs) to support survey and development work on rail infrastructure.

A reduced potential impact on services, improved access to hard-to-reach structures and the generation of richer, BIM compliant data are all key benefits of using this new technology. London Underground is embracing this technology and has already successfully carried out a number of projects through one of its maintenance contractors, Lanes Group, and has more in the pipeline.

“Digital technology, and the way it can be deployed using UAVs is changing our mindset,” says Andy McQueen, who heads up Lanes Group’s new professional services team. “In the future, rail contractors are likely to become just as much data management experts as track drainage and building maintenance experts. The opportunities to support rail clients are significant.”

Spy in the sky

Lanes Group, which operates a range of drainage and structure maintenance contracts for London Underground, is using the latest UAV technology, originally developed for military use in Germany and only just released for civil applications. Surveillance is still the name of the game but, increasingly, bridges, maintenance depots, power lines and drainage systems will be the focus of attention using ultra-HD digital cameras.

Captured images can be used to generate 3D point clouds, useful for generating 3D structural models, and CAD files, as well as being turned into orthogonal mosaics. Videos can be used to create fly-throughs to help with identifying obstructions, clashes and access issues.

Operators can capture the big picture from 100 or more metres away, or can swoop down to inspect structures in minute detail from just two metres. UAVs can even be flown inside large structures, provided the correct safety protocols are in place.

Thus new technology has significant practical advantages. A UAV survey of the roof at Amersham Station on the Metropolitan line – the first drone survey of a Tube station – was completed in one day by just two operatives.

To carry out the same survey by conventional means – getting boots on the ground – would have taken a team of four operatives up to five nights. In some cases, roof areas are so fragile that carrying out such inspections conventionally is almost impossible.

Direct comparison

There are now plans to expand the application of UAV surveys beyond obvious structures to London Underground’s track drainage systems. Lanes Group is trialling the idea and will first carry out a conventional full drainage survey around a major maintenance depot, then mapping the area from the air using a UAV.

Andy McQueen explained: “We will then compare the results. I am confident the exercise will show UAV surveys can be a useful technique to locate and plot catch pits, pump stations, and track drainage, and to create accurate georeferenced asset maps.”

Until now, plotting and managing assets like track drainage has been notoriously difficult and time-consuming, adding to maintenance costs and hindering effective capital investment decision-making.

UAV and digital image technology, as used by Lanes Group, has the potential to change that, with larger areas surveyed more quickly, more accurately, and with a lighter touch.